70 Analyses of Books. [July 



specimen, but he visited numerous museums and observed similar 

 fish. The remains of another species placed in his hands from 

 Greenside, near Glasgow, he describes under Megalichthys falcatus. 

 It is reasonable to suppose, as Dr. Hibbert suggests, that many- 

 remains which have been considered those of saurian reptiles, may 

 belong, to this genus which possesses the mixed organization of fish 

 and reptile. He instances what he considers several examples of this 

 kind of mistake. By the discovery of this genus, much light has been 

 thrown upon the nature of the localities in which the older carbonifer- 

 ous rocks were deposited; for we have only to study the anatomy and 

 habits of the recent Lepidosteus, a sauroid fish which dwells among 

 the lakes and rivers of the most thermal regions of America, in order 

 to be convinced that these fossil and recent fish, so analogous in 

 every respect, must have been placed in the same circumstances. 

 Copr elites occur at Burdiehouse abundantly, sometimes attaining to 

 a great size, and occasionally being diffused over a surface of lime- 

 stone to the extent of nearly a foot. These foecal remains are of a 

 pale yellow colour, and consist, according to Mr. Connell, of phos- 

 phate of lime, with some fluate of lime 85*08 ; carbonate of lime 

 10*78 ; silica 39 ; potash and soda -59 ; bituminous matter 3- 95 ; 

 with a trace of phosphate of magnesia and animal matter. 



The second portion of the memoir treats of the Burdiehouse strata, 

 with reference to their geological position, and is full of interesting 

 matter ; but to do justice to the details it would be necessary to read 

 them. It is proper to observe, however, that the author draws from 

 his researches the following inference in favour of the fresh water 

 origin of the strata. 



1. '' That it is by the presence or absence of acknowledged pelagic 

 moUusca, corallines, &c. that indications are afforded of the great 

 difference between fresh water and marine deposits. 



2. *^ That if along with marine moUusca or corrallines, we find 

 the plants of coal-fields in a quantity comparatively small, an 

 estuarian limestone may be inferred. 



3. " That if marine mollusca or corallines should be entirely 

 absent in a limestone, and if plants should be abundantly found in 

 it, an indication would be afforded of a calcareous deposit which took 

 place amidst the fresh- water rivers or lakes of primeval marshes ; 

 which indication would be still more favoured, if we should find in 

 addition recognised genera of fresh- water shells, the entomostraca of 

 stagnant marshes, or the fish incidental to coal-fields." 



He anticipates the objection of the possibility that molluscous 

 animals may yet be discovered, by observing, that they cannot occur 

 in any great abundance, and that their presence would indicate that 

 the fresh water lake had been merely connected with an ancient sea. 



The mode in which the formation was deposited, he supposes to 

 have been as follows : — 



Springs charged with carbonate of lime and issuing from deep 

 crevices, had mingled their mineral contents with some sluggish river 

 which flowed over a marshy tract principally overrun by the creep- 

 ing stems of Lycopodiaceae, and a dense overgrowth of ferns, con- 

 taining conspicuously Sphenopteris ajjlnis. Hence, the gradual 



